This invention relates to a system of monitoring the level of fluid remaining in a collapsible wall, intravenous (I.V.) bag so as to sound an alarm or to otherwise alert hospital personnel that the level of fluid remaining in the I.V. bag has decreased to a predetermined level.
In the treatment of many hospital patients, it is conventional to administer fluids and medication intravenously. Intravenous fluid is administered by inserting a needle or catheter into a vein of the patient (e.g., in the proximal forearm). Once the catheter is in place in a vein, it is typically taped or otherwise secured to the patient and is connected by means of flexible rubber or plastic tubing to a supply of liquid to be fed through the tubing and to be admixed with the blood flowing through the vein. Typically, the intravenous fluid supply is elevated on an I.V. pole or the like adjacent the patient's bed, wheelchair, stretcher, or may be carried by an ambulatory patient so that it has a sufficient hydrostatic pressure to overcome the pressure of the blood flowing through the vein. Typically, the I.V. container and tubing is equipped with a drip indicator and valve so that the rate at which the I.V. fluid is administered can be accurately regulated.
In recent years, the use of flexible wall bags has, for the most part, replaced glass or other rigid bottles as the containers for I.V. solutions. I.V. bags may come in a variety of volumes (e.g., 250 ml, 500 ml, 1 liter etc.) the I.V. bags are typically filled with a sterile liquid solution, such as a 5% dextrose and water solution, and have a sealed outlet into which a sterile probe connected to the tubing leading to the catheter implanted in the patient's vein may be inserted thereby to puncture the bag seal and to permit the I.V. solution to drain from the bag.
Oftentimes the flow rates for the I.V. solution or fluid is established by the treating physician such that a one liter bag may require many hours to be administered to the patient. Also, it is conventional to administer medication by injecting the medication into the bag by means of a hypodermic needle inserted through a puncturable seal provided in the bag wherein the medication is administered simultaneously with the I.V. solution. Oftentimes, the treating physician may direct that the medication by administered only after the patient has received a predetermined quantity of the I.V. solution. I.V. fluids are, of course, also used to increase a patient's fluid level in various treatment procedures, such as in administering plasma or whole blood, or in conducting fluid challenge tests.
In the event the I.V. solution is totally drained from the bag, blood backs up into the catheter and at least partially into the tubing connected to the catheter. This will result in clotting of the blood, other medical complications and, in psychological concerns to the patient. Thus, it is imperative for nurses to keep a regular and careful check to insure that a sufficient quantity of the I.V. solution remains in the bag.
However, nurses sometimes needlessly change the bag when ample quantities of the I.V. fluid remain in the bag and this results in waste of the remaining I.V. solution and in additional expense to the patient. Also, the patient may not get the full dosage of medication contained in the I.V. solution. Thus, nursing personnel must keep a vigilant check on the level of and flow rate of the I.V. solution.
Still further, patients may, during their sleep, dislodge the catheter from their vein or may pull the plastic tubing loose from the hub of the catheter thereby permitting the catheter to run dry and permitting the I.V. solution to rapidly drain from the bag, and/or to result in bleeding of the patient.
Because of the pain resulting from the insertion of an I.V. needle or catheter, hospital patients worry about the administration of I.V. solutions and whether the nursing staff will promptly change the I.V. bags when required.
I.V. infusion systems are currently available which continuously and positively control the administration of I.V. fluid to the patient. These prior I.V. infusion or monitoring systems are complicated. Typically, these I.V. infusion systems or monitors may either operate on the principle of counting the drops of I.V. solution discharged from the bag falling through the drip chamber of the drip meter provided in the tubing. Other I.V. administering and monitoring systems utilize a positive displacement pump operable at a very low, selectable flow rates to insure the administering of the fluid at a desired rate. However, all of the known I.V. infusion or monitoring systems are complex, complicated, and quite expensive. They all require an outside source of electrical power and they may present unnecessary electrical shock hazards to the patient. Of course, these systems may be useless in cases of power outages, or in large scale disasters (e.g., earthquakes) where no power source is available, or in forward battles in military combat. In many instances, only acute care hospital patients justify the expense of such sophisticated and complicated I.V. infusion or monitoring systems.
Still further, under present hospital economic and staffing constraints, registered nurses are responsible for a maximum number of patients. During busy periods, such as when several nurses are administering to a patient whose condition is deteriorating, other patients on the floor may not receive their full share of routine nursing functions, such as the monitoring of I.V. solutions. Because of the serious consequences which can result from an I.V. bag running dry or from the tubing becoming dislodged, increased pressures are imposed on nurses who are already working under stress at a high level of concentration and efficiency.